LOL! We could have a smarts smackdown but since I usually fold under
pressure like a lawnchair, I'll concede this one to Mike S.

--
Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
KG6RCR

On 11/13/2007 3:19 PM Brendan Slevin wrote:

> How many watts brighter is Mike S than Mike E and how does it relate to MPG
> increasing?
>
> :)
>
> Brendan
>
>
>
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM] On Behalf Of
> Michael Elliott
> Sent: Tuesday, November 13, 2007 3:12 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: Hid AUX lamps GoWesty's headlight upgrade kit
>
> Coolness. I knew all I had to do was to make an amateurish stab at the
> math and someone who knows a lot more than I would provide the real
> numbers. Thanks, Mike!
>
> --
> Mike "Rocket J Squirrel" Elliott
> 71 Type 2: the Wonderbus
> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
> 74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
> KG6RCR
>
> On 11/13/2007 3:06 PM Mike S wrote:
>
>> At 05:32 PM 11/13/2007, Michael Elliott wrote...
>>> So, how important is the difference between 160 or 300 Watts of power
>>> going to the headlights when compared to 100,000 watts moving the van?
>> The point is valid, but some math is missing.
>>
>> The useful BTU capacity of gasoline is reduced by the fact that engines
>> are very much less than 100% efficient, and there are also drivetrain
>> losses before any energy is used to move the car.
>>
>> 20% efficiency is in the ballpark, so we're talking about 20K Watts
>> actually being used. An A/C Vanagon has a maximum output of 67 HP, or 49
>> KW, and would  cruise at some fraction of that (1/3?) , so all of those
>> figures seem to be reasonable.
>>
>> 140 Watts of 12V power from the alternator is more than that from the
>> engine, because alternators, too, are not 100% efficient. 55% is a
>> reasonable ballpark, to that 140 W of DC takes ~250W of engine power.
>>
>> 250W / 20KW = 1.25%
>>
>> If a Vanagon gets 20 MPG, then the savings would be about the same as
>> getting an extra 1/4 MPG.
>>
>